RF Latex
OSR61105
4 x 24 mL
4 x 8 mL
R1
R2
RF Latex Buffer
RF Latex
Intended Use
System reagent for the quantitative determination of Rheumatoid Factor (RF) in human serum and plasma on Beckman Coulter AU analyzers.
Summary1,2,3
Rheumatoid factors (RF) are antibodies directed against antigenic determinants on the Fc fragment of IgG. These are usually IgM antibodies, but
may be IgG, IgA or IgE.
Rheumatoid factor sensitivity in rheumatoid arthritis varies from 30% in population-based studies to 70 – 80% in hospital-based studies, where the
disease tends to be more severe. Higher titres of RF are more specific for the diagnosis of rheumatoid arthritis (RA) and are more common in
patients with rapidly progressive joint destruction and in those with extraarticular manifestations such as subcutaneous rheumatic nodules. However,
RF is a non-specific test and a positive RF is observed in 1 – 5% of the healthy population at low titres and in 15 – 20% of elderly subjects with other
chronic disease states. Similarly a negative result does not exclude RA. Approximately 25% of patients with a diagnosed case of RA may present
with a negative result for RF.
A positive RF is also seen in autoimmune rheumatic diseases and in non-rheumatic conditions with variable frequency e.g. SLE, Sjögren’s
syndrome, subacute bacterial endocarditis and other bacterial infections, infectious hepatitis, chronic liver diseases, chronic active pulmonary
diseases, parasitic infections and viral infections.
Methodology
Immune complexes formed in solution scatter light in proportion to their size, shape and concentration. Turbidimeters measure the reduction of
incidence light due to reflection, absorption or scatter.
In this procedure, the decrease in light intensity transmitted (increase in absorbance) through particles suspended in solution is as a result of
complexes formed during the immunological reaction between the RF of the patient serum and the anti-RF IgG antibodies coated on the latex
particles.
System Information
e
e
AU400/400 /480, AU600,640/640 /680 and AU2700/5400/AU5800 Beckman Coulter Analyzers.
Reaction Principle
When a sample is mixed with R1 buffer and R2 IgG latex solution, RF reacts specifically with IgG coated on the latex particles to yield insoluble
aggregates. The absorbance of these aggregates is proportional to the RF concentration in the sample.
Reagents
Final Concentration of Reactive Ingredients:
Glycine buffer (pH 8.0)
Latex coated with human IgG
Preservative
170 mmol/L
< 0.5 %
0.09 %
Precautions
OSHA Classification: Irritant
For in vitro diagnostic use.
Do not ingest. Harmful if swallowed.
Exercise the normal precautions required for handling all laboratory reagents.
Biological materials of human origin contained in R2 were tested for Anti-HCV, HbsAg and Anti-HIV 1/2 on a single donor basis using FDA approved
methods and were found to be non-reactive. As there is no known test method that can offer complete assurance that products derived from human
blood will not transmit infectious agents, this product should be handled as a potentially infectious material.
Contains sodium azide as a preservative, which may react with lead joints in copper plumbing to form explosive compounds. Even though the
reagent contains minute quantities of sodium azide, drains should be well flushed with water when discarding the reagent.
Safety data sheet available for professional user on request.
Dispose of all waste material in accordance with local guidelines.
Preparation of Reagents
R1 is ready for use and can be placed directly on board the instrument. R2 should be mixed by inversion 5 – 10 times before placing on board the
instrument and at weekly intervals thereafter.
Storage and Stability
The unopened reagent is stable until the expiration date printed on the label when stored at 2 - 8°C.
Working reagent is stable for 60 days when stored in the refrigerated compartment of the analyzer.
Indications of Deterioration
Visible signs of microbial growth, gross turbidity, precipitate or change in color in the RF Latex reagent may indicate degradation and warrant
discontinuation of use.
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RF Latex
Specimen Collection and Preparation
Serum, Li-heparin, and EDTA plasma.
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Sample Storage and Stability
Stable in serum and plasma for:
1 day at 20 – 25°C
8 days at 4 – 8°C
3 months at -20°C (avoid repeated freezing and thawing)
Interfering Substances
Results of studies show that the following substances may interfere with this RF procedure:
The criteria for no significant interference is recovery within 10% of the initial value
Bilirubin:
No significant interference up to 40 mg/dL Bilirubin
Hemolysis:
No significant interference up to 500 mg/dL Hemolysate
Lipemia:
No significant interference up to 1000 mg/dL Intralipid*
* Intralipid, manufactured by KabiVitrium Inc., is a 20% IV fat emulsion used to emulate extremely turbid samples.
The information presented is based on results from Beckman Coulter studies and is current at the date of publication. Beckman Coulter Inc. makes
no representation about the completeness or accuracy of results generated by future studies. For further information on interfering substances, refer
5
to Young for a compilation of reported interferences with this test.
In very rare cases gammopathy, especially monoclonal IgM (Waldenström’s macroglobulinemia), may cause unreliable results.
Procedure
A complete list of test parameters and operational procedure can be found in the User’s Guide appropriate to the analyzer.
Materials Provided
System RF Latex Reagent
Materials required but not provided
RF Latex Calibrator (Cat. No. ODC0028)
0.9% Saline
Stability of Final Reaction Mixture
The Beckman Coulter chemistry analyzers automatically compute every determination at the same time interval.
Calibration
The frequency of calibration for the RF Latex procedure is every 30 days. Calibration of this procedure is accomplished by use of the RF Latex
6
Calibrator ODC0028, which is traceable to WHO International reference material, NIBSC 64/2.
For the zero calibrator use 0.9% saline.
Recalibration of this test is required when any of these conditions exist:
A reagent lot number has changed or there is an observed shift in control values.
Major preventative maintenance was performed on the analyzer.
A critical part was replaced.
Quality Control
During operation of the Beckman Coulter AU analyzer at least two levels of appropriate control material should be tested a minimum of once a day.
In addition, these controls should be tested after calibration with each new lot of reagent and after specific maintenance or troubleshooting steps
described in the appropriate User’s Guide. Quality control testing should be performed in accordance with regulatory requirements and each
laboratory’s standard procedure.
Results
Automatically printed out for each sample in IU/mL at 37°C.
Dynamic Range
The RF Latex procedure is linear from 10 to 120 IU/mL Samples exceeding the upper limit of linearity should be diluted with saline and repeated.
Prozone or hook effect may occur with high RF samples (300 – 2000 IU/mL). Prozone settings or data check parameters are required.
Expected Values7
Adult
≤ 14 IU/mL
th
This value is based on serum samples from 574 normal/healthy subjects (95 percentile).
Expected values may vary with age, sex, diet and geographical location. Each laboratory should determine its own expected values as dictated by
good laboratory practice.
For diagnostic purposes, results should always be assessed in conjunction with the patient's medical history, clinical examinations and other
findings.
Specific Performance Characteristics
The following data was obtained using the RF Latex reagent on Beckman Coulter AU analyzers according to established procedures. Results
obtained in individual laboratories may differ.
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RF Latex
9
Precision
8
Estimates of precision, based on CLSI recommendations, are consistent with typical performance. The within run precision is less than 10% CV for
RF values ≤ 20 IU/mL, less than 5% CV for RF values > 20 IU/mL and total precision is less than 10% CV. Assays of control material were carried
out and data reduced following CLSI guidelines above.
N= 80
Mean, IU/mL
10.26
20.06
76.87
114.81
Within run
SD
0.38
0.45
0.75
0.93
Total
CV%
3.72
2.24
0.97
0.81
SD
0.77
0.79
2.04
2.97
CV%
7.51
3.96
2.66
2.59
9
Method Comparison
Serum and plasma samples were used to compare this System RF Latex Reagent. The table below demonstrates representative performance on
AU analyzers.
Y Method
AU640
X Method
Method 2
Slope
0.996
Intercept (IU/mL)
-1.217
Correlation Coeff. (r)
0.996
No. of Samples (n)
55
Range (IU/mL)
6.30 – 103.20
Sensitivity
The lowest detectable level was estimated as follows:
Analyzer
Lowest Detectable Level (IU/mL)
AU2700
1.38
AU640
1.42
AU400/680
2.22
Functional Sensitivity
Precision results (40-fold determination) for a level < 5.0 IU/mL have a CV of < 20% for each application.
Mean Concentration (IU/mL)
SD
CV%
AU400
2.74
0.46
17.1
AU2700
3.09
0.53
17.2
AU640
3.22
0.54
16.9
Limit of Detection
The Limit of Detection (LOD) for RF was determined to be 4.74 IU/mL on the AU5800 analyzer. This was determined according to CLSI protocol
10
EP17-A.
Limit of Qualtitation
The Limit of Quantitation (LOQ) for RF was determined to be 7.10 IU/mL on the AU5800 analyzer. This was determined according to CLSI protocol
10
EP17-A and represents the lowest concentration of RF that can be measured with a total imprecision of 20%.
References
1.
2.
Ismail AA, Snowden N. Autoantibodies and specific serum proteins in the diagnosis of rheumatological disorders. Ann Clin Biochem 1999;36:565-578.
Mierau R, Genth E. Autoantibodies in rheumatoid arthritis. In: Thomas L, ed. Clinical laboratory diagnostics. Use and assessment of clinical laboratory
results. Frankfurt/Main: TH-Books Verlagsgesellschaft, 1998:810-813.
3. Shimmerling RH, Delbanco TL. The rheumatic factor: An analysis of Clinical Utility. The American Journal of Medicine, 1991; 91:530.
4. Ehret W, Heil W, Schmitt Y, Töpfer G, Wisser H, Zawta B, et al. Use of Anticoagulants in Diagnostic Laboratory Investigations and Stability of Blood,
Plasma and Serum Samples. WHO/DIL/LAB/99.1 Rev.2:41pp.
5. Young DS. Effects of drugs on clinical laboratory tests, 6th ed. AACC Press, 2000.
6. Anderson SG, Bentzon MW, Houba V, Krag P. International reference preparation of rheumatoid arthritis serum. Bull Wld Hlth Org 1970;42: 311-318.
7. In-house data on file.
8. CLSI/NCCLS. Evaluation of precision performance of clinical chemistry devices; approved guideline. CLSI/NCCLS document EP5-A;1999.
9. Data is on file for specific AU analyzers.
10. CLSI, protocol for determination of limit of detection and limit of quantitation; Approved guidline, EP17-A, 2004.
Manufactured by: Beckman Coulter, Inc., 250 S. Kraemer Blvd. Brea, CA 92821, USA
BAOSR6x105.05
2012-10
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